On Tue, Apr 7, 2020 at 1:46 PM kjansen387 <kjansen387@xxxxxxxxx> wrote: > > Hello, > > I'm using btrfs on fedora 31 running 5.5.10-200.fc31.x86_64 . > > I've moved my workload from md raid5 to btrfs raid1. > # btrfs filesystem show > Label: none uuid: 8ce9e167-57ea-4cf8-8678-3049ba028c12 > Total devices 5 FS bytes used 3.73TiB > devid 1 size 3.64TiB used 2.53TiB path /dev/sde > devid 2 size 3.64TiB used 2.53TiB path /dev/sdf > devid 3 size 1.82TiB used 902.00GiB path /dev/sdb > devid 4 size 1.82TiB used 902.03GiB path /dev/sdc > devid 5 size 1.82TiB used 904.03GiB path /dev/sdd > > # btrfs fi df /export > Data, RAID1: total=3.85TiB, used=3.72TiB > System, RAID1: total=32.00MiB, used=608.00KiB > Metadata, RAID1: total=6.00GiB, used=5.16GiB > GlobalReserve, single: total=512.00MiB, used=0.00B > > After moving to btrfs, I'm seeing freezes of ~10 seconds very, very > often (multiple times per minute). Mariadb, vim, influxdb, etc. > > See attachment for a stacktrace of vim, and the dmesg output of 'echo w > > /proc/sysrq-trigger' also including other hanging processes. > > What's going on.. ? Hope someone can help. How busy are the databases? What are the mount options for this volume? I think there is some kind of write contention possible if there's heavy fsync writes, since the tree log is per subvolume? (Maybe a developer can describe this correctly if I haven't.) A possible work around is putting each database in its own subvolume. -- Chris Murphy
